Epiphany is one of the Chuch’s major and spectacular feasts. It occurs on January 6th, the final day of the 12 days of Christmas (in some locations it is transferred to the Sunday between January 2 – 8). In some places it is also called Twelfth night or Three Kings Day. This is the day the Church commemorates the Magi arriving to give homage to the newborn King of Kings with their gifts of gold, frankincense, and myrrh, symbolic of all the Gentile nations coming into the Kingdom of God. In many places around the world, this was the traditional day of gift-giving in celebration of Christmas.
There is a long-standing Epiphany tradition of marking churches, homes, schools, and other buildings with a special ‘holy formula’ over the entryway using chalk that has been blessed for this purpose on Epiphany. This formula includes the current year along with the initials C, M, and B in the order shown below.
20 + C + M + B + 18
The C, M, and B are placed in between the numbers of the current year, with crosses in between each symbol. The three letters have two significations: the invocation Christus Mansionem Benedicat (Christ bless this house), as well as the first initial of the names of the three Magi: Caspar, Melchior, and Balthazar.
Click here for the rest of the article (by Gretchen Filz). Happy Three Kings!